This invention relates to insulated electrical conductors which can be used as interconnecting or hookup wire or as components of multiconductor cables.
Many performance criteria are important in an insulated electrical wire. A number of such criteria that are especially important in the aircraft industry, include weight and space; arc-track resistance; abrasion and cut-through resistance; temperature rating; flexibility and stiffness; smoke generation and flammability; and chemical resistance.
The relative importance of these criteria varies with the particular application, and it may not be possible to have one insulation system that is the best in all respects. For example, good abrasion resistance and high cut-through resistance are usually obtained with high modulus materials, whereas better flexibility and low-springback generally require low modulus materials. Consequently, insulation systems offer different balances of properties, excelling in different respects.
In the effort of researchers to find a better balance of properties, two main approaches have been followed. First, effort has been devoted to the development of new or modified materials with improved insulating properties. In this regard, fluoropolymers and polyimides have been widely used. Secondly, combinations of materials have been evaluated in attempts to realize in the composite the better properties of the various components. For example, braided fibers have been used as an external jacketing to improve mechanical properties and protect underlying insulation.
Despite many earlier attempts to develop insulating systems, a need exists to satisfy the demands of increasingly complex electrical and electronic systems used in industrial and aerospace applications.